A conventional three-side trimmer of this type is disclosed in JP2003-71779A. As shown in FIG. 6, this three-side trimmer has a rotating table unit 71 that receives a bound material 70 from a bound material feed unit (not shown) at a predetermined position to be positioned there and rotates the bound material at every predetermined angle (90 degrees) in a supporting manner to arrange the bound material at three positions respectively, i.e., a top edge cutting position, front edge cutting position and bottom edge cutting position, and a trimming unit 72 that is arranged so as to be movable in a direction close to or away from the rotating table unit 71 and has a cutting position where it becomes close to the rotating table unit 71 for cutting a top edge section 70a, bottom edge section 70b and front edge section 70c of the bound material 70 respectively and a stand-by position where it is away from the rotating table unit 71.
The rotating table unit 71 has an top surface that can support a section of the bottom surface of the bound material 70 except for the top edge section 70a, bottom edge section 70b and the front edge section 70c, and has a table 73, on which the bound material 70 is placed, mounted on the top surface. The table 73 is composed of an L-shaped metal plate having a flat section on which the bound material 70 is placed and an upright section 73a joined to one side edge of the flat section. The upright section 73a of the table 73 functions as a positioning plate to which a back 70d of the bound material 70 contacts.
Although not shown, a vertical rotating shaft is mounted at the bottom surface of the table 73, wherein the rotating shaft is held so as to be rotatable by a bearing. Further, a motor is coupled to the rotating shaft, whereby the table 73 is rotatably driven by the motor.
Moreover, a pressure plate 74 is arranged so as to be capable of moving up and down at a position opposite to the rotating shaft above the table 73. It takes a stand-by position spaced from the bound material 70 and a working position for pressing the bound material 70 to the table 73. The pressure plate 74 can rotate at the working position with the table 73 and the bound material 70.
The trimming unit 72 is provided with a frame 75, a trimming table element 76 attached to the frame 75 and a blade receiving plate 77 fixed to the top surface of the trimming table element 76. Further, a trimming cutter 78 is arranged so as to be capable of moving up and down by a driving mechanism 79 at a position opposite to the blade receiving plate 77 above the trimming table element 76. The trimming cutter 78 takes a non-cutting position spaced from the blade receiving plate 77 and a cutting position for pressing the edge of the cutter to the blade receiving plate 77.
Although not shown, a pressure member is arranged so as to be capable of moving up and down above the trimming table element 76. It takes a first position spaced from the bound material 70 and a second position for pressing the bound material 70 to the trimming table element 76. The pressure member takes the second position when the trimming cutter 78 moves from the non-cutting position to the cutting position, while it takes the first position when the trimming cutter 78 moves from the cutting position to the non-cutting position.
The frame 75 of the trimming unit 72 is coupled to a motor 80 via a feed screw 81. The trimming unit 72 reciprocates between the cutting position and the stand-by position by the drive of the motor 80.
The operation of each of the rotating table unit 71, the trimming unit 72 and the motor 80 is controlled, whereby the trimming unit 72 moves from the stand-by position to the cutting position every time the bound material 70 is arranged at the top edge cutting position, front edge cutting position and the bottom edge cutting position, to thereby respectively cut the top edge section 70a, the front edge section 70c and the bottom edge section 70b of the bound material 70.
According to the conventional three-side trimmer, the bound material 70 is received from the bound material feed unit to the table 73 and positioned thereon, regardless of length-width ratio (the ratio of the length between the top edge 70a and the bottom edge 70b to the length between the front edge 70c and the back 70d), while it keeps a fixed positional relationship with respect to the rotation shaft of the table 73. FIGS. 7 and 8 are plan views for explaining this state. FIG. 7 shows a state of the movement of the bound material 70 and the trimming cutter 78 during the trimming operation of the bound material 70 of 300 mm×200 mm ((the length between the top edge 70a and bottom edge 70b)×(the length between the back 70d and front edge 70c)), while FIG. 8 shows a state of the movement of the bound material 70′ and the trimming cutter 78′ during the trimming operation of the bound material 70′ of 200 mm×300 mm ((the length between the top edge 70a′ and bottom edge 70b′)×(the length between the back 70d′ and front edge 70c′)). In FIGS. 7 and 8. (A) shows a state where the bound material is positioned, while (B) shows a state where the bound material is rotated at three cutting positions respectively, wherein X represents the bound material at the top edge cutting position, Y represents the bound material at the front edge cutting position and Z represents the bound material at the bottom edge cutting position. Further, O represents the center of rotation of the table.
As easily understood from FIGS. 7 and 8, when the bound material in which the length between the top edge and the bottom edge is its short side and the length between the back and the front edge is its long side is cut, the length L of the blade of the trimming cutter 78 equals to 300 mm that is substantially the same as the length of the long side of the bound material, and further, a short moving distance of the trimming cutter 78 is enough in this construction. However, when the bound material in which the length between the top edge and the bottom edge is its long side and the length between the back and the front edge is its short side is cut, the trimming cutter 78′ having the length L of the blade is 480 mm is required, and further, the moving distance of the trimming cutter 78′ is required to be increased.
Specifically, in order to cut various bound materials each having a different length-width ratio in the conventional three-side trimmer, the required construction is such that a heavy trimming cutter having a long length of the blade can be moved in a long distance. With this construction, the whole structure of the three-side trimmer should be made to have greater energy consumption and to occupy much more space.